* The Visitors
* The Anomaly
* The Forever Man
* The Gateway Gods
* The Time Runner
Short Stories
* "The Last Voyage of the USS Monitor"
* "The Last Supper"
* "The Third Commandment"
* "The Fourth Kind"
* "The Fifth Horseman"
Essays and Articles
* "The Evolution of the Human Race"
* "The Future of Artificial Intelligence"
* "The Search for Extraterrestrial Life"
* "The Meaning of Life"
* "The Nature of Reality"